WO2020262084A1

WO2020262084A1 - Leakage detection device and power system for vehicle

Info

Publication number: WO2020262084A1
Application number: PCT/JP2020/023448
Authority: WO
Inventors: 中山　正人; 泰輔濱田
Original assignee: 三洋電機株式会社
Priority date: 2019-06-28
Filing date: 2020-06-15
Publication date: 2020-12-30
Also published as: US12072393B2; US20220357408A1; CN114144687A; JP7554191B2; JPWO2020262084A1

Abstract

Provided is a leakage detection device (10), wherein, in order to enable highly accurate leakage detection even when the voltage waveform at a measurement point rises/falls overall, one end of a coupling capacitor (Cc) is connected to a current path of a power storage unit (20) connected to a load (2) in a state where the coupling capacitor (Cc) is insulated from the ground. A voltage output unit (11a, G1) generates a periodic voltage that changes periodically, and applies the generated periodic voltage to the other end of the coupling capacitor (Cc) via an impedance element (R1). A voltage output unit (11b) measures the voltage at a connection point between the coupling capacitor (Cc) and the impedance element (R1). A leakage determination unit (11c) estimates at least one among the upper peak value and the lower peak value at a certain time, calculates a peak value between the upper peak value and the lower peak value whose time axes are virtually aligned, and determines the presence or absence of leakage between the current path of the power storage unit (20) and the ground.

Description

Leakage detector, vehicle power supply system

The present invention relates to an earth leakage detection device for detecting an earth leakage of a load insulated from the ground, and a vehicle power supply system.

In recent years, hybrid vehicles (HVs), plug-in hybrid vehicles (PHVs), and electric vehicles (EVs) have become widespread. These electric vehicles are equipped with a high-voltage drive battery (traction battery) in addition to an auxiliary battery (generally a 12V output lead battery). In order to prevent electric shock, a high-voltage circuit including a high-voltage drive battery, an inverter, and a traveling motor is insulated from the vehicle body (chassis ground).

A Y capacitor is inserted between the positive wiring on the vehicle side of the high-voltage circuit and the chassis ground, and between the negative wiring on the vehicle side of the high-voltage circuit and the chassis ground, and is supplied to the load on the vehicle side from the high-voltage drive battery. The power supply is stabilized. An earth leakage detection device that monitors the insulation resistance between the high-power circuit and the chassis ground to detect an earth leakage is installed.

In the AC type earth leakage detection device, a pulse voltage is applied to the positive electrode terminal or the negative electrode terminal of the drive battery via a resistor and a coupling capacitor, and the voltage at the connection point between the resistor and the coupling capacitor is measured. Detects the presence or absence of electric leakage (see, for example, Patent Document 1).

JP-A-2010-178422

In the above configuration in the AC method, the voltage at the measurement point may deviate from the measurement range when the leakage state suddenly changes, such as when the main relay (contactor) connected between the battery side and the vehicle side is opened and closed. In the process of returning the voltage of the measurement point to the measurement range, a period in which the voltage waveform of the measurement point rises / falls at a constant speed occurs. During this period, the peak peak value between the upper peak value and the lower peak value of the voltage waveform at the measurement point expands and contracts regardless of the influence of noise, and stable leakage detection becomes difficult.

The present disclosure has been made in view of such a situation, and an object of the present invention is a technique for enabling highly accurate leakage detection even when the voltage waveform at a measurement point is generally rising / falling in the leakage detection device. Is to provide.

In order to solve the above problems, the leakage detection device of one aspect of the present disclosure includes a coupling capacitor whose one end is connected to the current path of the power storage unit connected to the load in a state of being insulated from the ground, and a period. A voltage output unit that generates a periodic voltage that changes in a rhythmic manner and applies it to the other end of the coupling capacitor via an impedance element, and measures the voltage at a connection point between the coupling capacitor and the impedance element. Presence or absence of leakage between the current path of the capacitor unit and the ground based on the peak value between the voltage measuring unit and the upper peak value and the lower peak value of the voltage waveform measured by the voltage measuring unit. It is provided with a leakage determination unit for determining. The earth leakage determination unit estimates at least one of the upper peak value and the lower peak value at a certain time, and determines the peak peak value between the upper peak value and the lower peak value whose time axes are virtually aligned. calculate.

According to the present disclosure, in the leakage detection device, highly accurate leakage detection is possible even when the voltage waveform at the measurement point rises / falls as a whole.

It is a figure for demonstrating the configuration of the power-source system including the leakage detection device which concerns on embodiment. 2 (a)-(b) are diagrams for explaining the difference in the calculation method of the peak peak value of the measured voltage waveform between the comparative example and the control example 1. It is a figure which shows an example of the measured voltage waveform when the main relay is turned on. 4 (a)-(b) are diagrams for explaining the behavior of the peak peak value when the measured voltage waveform is rising at a constant speed in Comparative Example and Control Example 1. 5 (a)-(b) is a diagram for explaining a specific example of reliability evaluation of leakage determination using two adjacent peak peak values. 6 (a)-(b) are diagrams for explaining the difference in the calculation method of the peak peak value of the measured voltage waveform between the control example 1 and the control example 2. 7 (a)-(b) are waveform diagrams showing an example of the peak peak value with respect to the frequency of the measured voltage in the control example 1 and the control example 2. 8 (a)-(b) are graphs showing an example of the gain characteristic with respect to the frequency of the measured voltage in the control example 1 and the control example 2.

FIG. 1 is a diagram for explaining the configuration of the power supply system 5 including the earth leakage detection device 10 according to the embodiment. The power supply system 5 is mounted on an electric vehicle. The power supply system 5 is provided separately from the auxiliary battery (usually, a lead battery having a 12V output is used) in the electric vehicle. The power supply system 5 includes a high-voltage power storage unit 20 and an earth leakage detection device 10. The power storage unit 20 includes a plurality of cells E1-En connected in series. As the cell, a lithium ion battery cell, a nickel hydrogen battery cell, a lead battery cell, an electric double layer capacitor cell, a lithium ion capacitor cell, or the like can be used. Hereinafter, in the present specification, an example in which a lithium ion battery cell (nominal voltage: 3.6-3.7 V) is used is assumed.

The electric vehicle is equipped with an inverter 2 and a motor 3 as a high voltage load. The positive electrode of the power storage unit 20 and one end of the inverter 2 are connected by the positive wiring Lp, and the negative electrode of the power storage unit 20 and the other end of the inverter 2 are connected by the negative wiring Lm. The positive main relay MRp is inserted into the positive wiring Lp, and the negative main relay MRm is inserted into the negative wiring Lm. The positive side main relay MRp and the negative side main relay MRm function as contactors for controlling conduction / disconnection between the power storage unit 20 and the high voltage load in the electric vehicle. It is also possible to use a semiconductor switch with high withstand voltage and high insulation instead of the relay.

The inverter 2 is a bidirectional inverter connected between the power storage unit 20 and the motor 3. During power running, the inverter 2 converts the DC power supplied from the power storage unit 20 into AC power and supplies it to the motor 3. At the time of regeneration, the AC power supplied from the motor 3 is converted into DC power and supplied to the power storage unit 20. For the motor 3, for example, a three-phase AC motor is used. During power running, the motor 3 rotates according to the AC power supplied from the inverter 2. At the time of regeneration, the rotational energy due to deceleration is converted into AC power and supplied to the inverter 2.

The power storage unit 20 is mounted on the electric vehicle in a state of being insulated from the chassis ground of the electric vehicle. The auxiliary battery is mounted on the electric vehicle with the negative electrode conducting with the chassis ground. From the positive main relay MRp, the positive wiring Lp on the inverter 2 side and the chassis ground are connected via the positive Y capacitor Cp. Further, from the negative side main relay MRm, the negative wiring Lm on the inverter 2 side and the chassis ground are connected via the negative side Y capacitor Cm. The positive Y capacitor Cp and the negative Y capacitor Cm insulate the positive wiring Lp and the chassis ground and between the negative wiring Lm and the chassis ground in a DC manner, and stabilize the voltages of the positive wiring Lp and the negative wiring Lm, respectively. Has the effect of causing.

When the power storage unit 20 is ideally insulated from the chassis ground, the intermediate potential of the power storage unit 20 is maintained near the potential of the chassis ground. For example, when the voltage across the power storage unit 20 is 250V, the positive electrode potential of the power storage unit 20 is maintained at around + 125V, and the negative electrode potential is maintained at around -125V. There is a risk of electric shock if a human touches the exposed conductive portion of the electric vehicle while the high-voltage power storage unit 20 and the chassis ground are conducting. Therefore, in an electric vehicle equipped with a high-voltage power storage unit 20, it is necessary to mount an earth leakage detection device 10 to monitor the insulation state between the current path of the power storage unit 20 connected to the high-voltage vehicle load and the chassis ground. There is. In FIG. 1, the insulating state between the positive wiring Lp and the chassis ground is represented by the positive leakage resistance Rlp, and the insulating state between the negative wiring Lm and the chassis ground is represented by the negative leakage resistance Rlm.

The leakage detection device 10 includes a coupling capacitor Cc, a first resistor R1, an AND gate G1, a first Zener diode ZD1, a second resistor R2, a first operational amplifier OP1, a second Zener diode ZD2, and a control unit 11. The control unit 11 includes an oscillation unit 11a, a voltage measurement unit 11b, and an earth leakage determination unit 11c. The control unit 11 can be composed of, for example, a microcomputer and a non-volatile memory (for example, EEPROM, flash memory).

One end of the coupling capacitor Cc is connected to the current path of the power storage unit 20. In the example shown in FIG. 1, one end of the coupling capacitor Cc is connected to the negative electrode of the power storage unit 20. One end of the coupling capacitor Cc may be connected to the positive electrode of the power storage unit 20, or may be connected to any node of a plurality of cells E1-En in the power storage unit 20. The other end of the coupling capacitor Cc is connected to the output end of the voltage output unit via the first resistor R1. The connection point between the other end of the coupling capacitor Cc and the first resistor R1 is the measurement point A. In addition, another impedance element may be used instead of the 1st resistor R1.

In FIG. 1, an aluminum electrolytic capacitor that can increase the capacity at a relatively low cost is used for the coupling capacitor Cc. The aluminum electrolytic capacitor has polarity, and in FIG. 1, the positive electrode of the aluminum electrolytic capacitor is connected to the measurement point A, and the negative electrode of the aluminum electrolytic capacitor is connected to the negative electrode of the power storage unit 20. The coupling capacitor Cc may be configured by connecting a plurality of aluminum electrolytic capacitors in series. In this case, even if one capacitor is short-circuited, DC insulation can be maintained by the remaining capacitors.

The voltage output unit generates a periodic voltage that changes periodically, and applies the generated periodic voltage to the other end of the coupling capacitor Cc via the first resistor R1. Hereinafter, in the present specification, an example in which a rectangular wave voltage is used as the periodic voltage is assumed.

The voltage output unit includes an oscillation unit 11a and an AND gate G1. The oscillating unit 11a includes a multivibrator and a local oscillator, and generates a rectangular wave having a preset frequency. The rectangular wave voltage generated by the oscillating unit 11a is input to the first input terminal of the AND gate G1. The second input terminal of the AND gate G1 is connected to the power supply potential Vcc. The AND gate G1 outputs a high level (power supply potential Vcc) when the rectangular wave voltage input to the first input terminal is high level, and when the rectangular wave voltage input to the first input terminal is low level, Outputs low level (ground potential). The ground potential is connected to the chassis ground. Hereinafter, an example in which the power supply potential Vcc is 5 V and the ground potential is 0 V is assumed.

The AND gate G1 functions as a buffer that separates the control unit 11 and the measurement point A. The AND gate G1 is an example of a buffer. For example, an OR gate or a voltage follower may be used instead of the AND gate. When an OR gate is used, a ground potential is connected to the second input terminal of the OR gate.

The first Zener diode ZD1 is connected between the connection point between the output terminal of the AND gate G1 and the first resistor R1 and the chassis ground.

The measurement point A is connected to the non-inverting input terminal of the first operational amplifier OP1 via the second resistor R2. The inverting input terminal and the output terminal of the first operational amplifier OP1 are connected. The first operational amplifier OP1 functions as a voltage follower having an amplification factor of 1 and performing only impedance conversion. The first operational amplifier OP1 outputs the voltage at the measurement point A to the voltage measuring unit 11b. A second Zener diode ZD2 is connected between the connection point between the non-inverting input terminal of the first operational amplifier OP1 and the second resistor R2 and the chassis ground.

In the above-mentioned first Zener diode ZD1 or second Zener diode ZD2, an overvoltage is applied to the AND gate G1 or the first operational amplifier OP11 due to the opening / closing of the main relays MRp and MRm and the load fluctuation of the power supply system 5. To prevent.

The voltage measuring unit 11b measures the voltage at the measuring point A. The voltage measuring unit 11b includes an A / D converter, and the A / D converter includes an analog voltage at the measurement point A at a timing synchronized with the timing of the rising edge and the falling edge of the rectangular wave voltage generated by the oscillating unit 11a. Is sampled and the sampled analog voltage is converted to a digital value. The voltage sampled at the timing of the rising edge of the square wave voltage corresponds to the lower peak value of the measured voltage waveform, and the voltage sampled at the timing of the falling edge of the square wave voltage is the measured voltage waveform. Corresponds to the upper peak value of. In consideration of the bluntness of the rectangular wave voltage, the timing at which the lower peak value should be sampled and the timing at which the upper peak value should be sampled may be adjusted. The A / D converter outputs a digital value obtained by converting the analog voltage of the measurement point A to the leakage determination unit 11c.

The leakage determination unit 11c determines whether or not there is an electric leakage between the current path of the power storage unit 20 and the chassis ground based on the voltage at the measurement point A measured by the voltage measurement unit 11b. If the peak peak value indicated by the difference between the upper peak value and the lower peak value is smaller than the set value, the electric leakage determination unit 11c determines that an electric leakage has occurred between the current path of the power storage unit 20 and the chassis ground. To do. The set value is determined based on the peak value of the measured voltage waveform at the time of leakage, which is derived in advance by an experiment or simulation by the designer. When an electric leakage occurs between the current path of the power storage unit 20 and the chassis ground, an alternating current flows from the AND gate G1 to the coupling capacitor Cc via the first resistor R1 acting as a detection resistor. When a current flows through the first resistor R1, the voltage amplitude at the measurement point A is reduced due to the voltage drop.

In the embodiment, the earth leakage determination unit 11c estimates at least one of the upper peak value and the lower peak value at a certain time, and is between the upper peak value and the lower peak value whose time axes are virtually aligned. Calculate the peak peak value.

(Control example 1)
In control example 1, the leakage determination unit 11c measures the voltage value measured at a time that should be measured one time before the specific upper peak value and one time after the specific upper peak value. The virtual lower peak value is calculated by averaging the voltage values measured at the time when it should be done. The earth leakage determination unit 11c calculates the peak peak value between the specific upper peak value and the virtual lower peak value.

Further, the leakage determination unit 11c measures the voltage value measured at a time that should be measured one time before the specific lower peak value and one time after the specific lower peak value. The virtual upper peak value is calculated by averaging the voltage values measured at the appropriate time. The earth leakage determination unit 11c calculates the peak peak value between the specific lower peak value and the virtual upper peak value.

2 (a)-(b) are diagrams for explaining the difference in the calculation method of the peak peak value of the measured voltage waveform between the comparative example and the control example 1. FIG. 2A shows a method of calculating the peak peak value of the measured voltage waveform in the comparative example, and FIG. 2B shows a method of calculating the peak peak value of the measured voltage waveform in the control example 1. In the comparative example shown in FIG. 2 (a), the difference between the two measured time-adjacent upper peak values V _H 1 and the lower peak value V _L 2 is defined as the peak peak value Vpp. In the control example 1 shown in FIG. 2 (b), the measured upper peak value V _H 1 and the two lower peak values V _L 1 and the lower peak value V _L 2 sandwiching the upper peak value V _H 1 are sandwiched. The difference from the lower peak average value _VL μ obtained by averaging is defined as the peak peak value Vpp. In the former, the timings of the upper peak value V _H 1 and the lower peak value V _L 2 do not correspond, but in the latter, the timings of the upper peak value V _H 1 and the lower peak mean value V _L μ correspond.

FIG. 3 is a diagram showing an example of the measured voltage waveform when the main relays MRp and MRm are turned on. When the main relays MRp and MRm are turned on, the voltage of the power storage unit 20 fluctuates greatly, and accordingly, a charging current flows from the voltage output unit to the coupling capacitor Cc via the first resistor R1. In this case, the voltage at the measurement point A drops significantly and deviates significantly below the input voltage range (0 to 5V) of the first operational amplifier OP1 that defines the measurement range of the voltage measuring unit 11b. The voltage waveform at the measurement point A rises from outside the measurement range as the charging current of the coupling capacitor Cc decreases. It rises sharply at the beginning and then slowly rises at a constant speed from the middle. When the charging of the coupling capacitor Cc is completed, the center voltage of the measurement point A returns to the intermediate potential (2.5V) of the measurement range. When the leakage resistance Rlp is large, it may take 30 seconds or more for the entire voltage waveform at the measurement point A to return to the measurement range (0 to 5V).

Note that the voltage at measurement point A may deviate above the measurement range. When the main relays MRp and MRm are turned on or off while the coupling capacitor Cc is charged for some reason, a discharge current flows from the coupling capacitor Cc through the first resistor R1 in the direction of the voltage output unit. In this case, the voltage at the measurement point A rises significantly and deviates significantly above the measurement range. The voltage waveform at the measurement point A decreases from outside the measurement range as the discharge current of the coupling capacitor Cc decreases. It descends steeply at the beginning, and then slowly descends at a constant speed from the middle. When the discharge of the coupling capacitor Cc is completed, the center voltage of the measurement point A returns to the intermediate potential (2.5V) of the measurement range.

FIGS. 4 (a)-(b) are diagrams for explaining the behavior of the peak peak value when the measured voltage waveform is rising at a constant speed in Comparative Example and Control Example 1. FIG. 4A shows the behavior of the peak peak value in the comparative example, and FIG. 4B shows the behavior of the peak peak value in the control example 1.

In the comparative example, the amplitude of the peak peak value Vpp expands or contracts in the process of increasing the measured voltage waveform. In the example shown in FIG. 4A, the first peak peak value Vpp1 defined by the difference between the first upper peak value V _H1 and the first lower peak value V _L 1 is the second upper peak value V _H 2. If it is set to a value smaller than the second peak-to-peak value Vpp2 defined by a first difference between the lower peak value V _{L 1.} The second peak peak value Vpp 2 is larger than the third peak peak value Vpp 3 defined by the difference between the second upper peak value V _H 2 and the second lower peak value V _L 2. As described above, in the comparative example, the amplitude of the peak peak value Vpp alternately repeats expansion and contraction, and the entire measured voltage waveform rises. The expansion and contraction of the amplitude of this peak peak value Vpp occurs regardless of the influence of noise.

In Control Example 1, the amplitude of the peak peak value Vpp is kept constant in the process of increasing the measured voltage waveform. 4 In the example shown in (b), the first peak-to-peak value which is defined by the difference between the first upper peak value V _{H 1} and the first lower peak average value V _L μ1 Vpp1, first upper peak average value V _H The second peak peak value Vpp2 defined by the difference between μ1 and the second lower peak value V _{L2, and} the difference between the second upper peak value _VH 2 and the second lower peak mean value V _L μ2. The amplitudes of the third peak peak value Vpp3 are substantially equal. As described above, in the control example 1, the entire measured voltage waveform rises while the amplitude of the peak peak value Vpp is kept constant.

In Control Example 1, the earth leakage determination unit 11c can evaluate the reliability of the earth leakage determination by comparing two adjacent peak peak values Vpp with each other. The earth leakage determination unit 11c enables the earth leakage determination when two adjacent peak peak values Vpp correspond, and invalidates the earth leakage determination when the two adjacent peak peak values Vpp do not correspond. In Control Example 1, if the voltage at the measurement point A is an ideal voltage that is not affected by noise, the two adjacent peak peak values Vpp should be substantially equal. Conversely, when two adjacent peak peak values Vpp do not substantially match, it can be said that the voltage at the measurement point A is greatly affected by noise. It can be said that the leakage determination based on the voltage at the measurement point A, which is greatly affected by noise, has low reliability. Therefore, the result of the earth leakage determination executed in such a low reliability state is treated as invalid. Alternatively, if the reliability is low, the leakage determination itself is stopped.

5 (a)-(b) are diagrams for explaining a specific example of reliability evaluation of electric leakage determination using two adjacent peak peak values Vpp. When the motor 3 in the electric vehicle starts regenerative power generation, the voltage of the power storage unit 20 momentarily rises due to the electric power generated by the motor 3. Further, when the electric vehicle accelerates, the rotation speed of the motor 3 increases, and the voltage of the power storage unit 20 momentarily decreases due to the increase in the electric power supplied to the motor 3. Such a momentary voltage fluctuation of the power storage unit 20 passes through the coupling capacitor Cc as vehicle noise and is superimposed on the voltage at the measurement point A.

FIG. 5A shows the measured voltage waveform when noise is not superimposed. In FIG. 5A, adjacent first peak peak value Vpp1 and second peak peak value Vpp2, adjacent second peak peak value Vpp2 and third peak peak value Vpp3, and adjacent third peak peak value Vpp3 and third The four peaks and peak values Vpp4 are substantially the same. It should be noted that even when the entire measured voltage waveform fluctuates at a constant speed (that is, fluctuates in a sufficiently long period) as shown in FIG.

FIG. 5B shows a measured voltage waveform when noise is superimposed. In FIG. 5B, regenerative power generation by the motor 3 occurs near the timing at which the second lower peak value _VL 2 is measured, and the second lower peak value _VL 2 is affected by noise. It is detected as a value higher than the original value. In this case, the second peak-to-peak value using a second lower peak value _{V L} 2 Vpp2 has become smaller than the first peak peak Vpp1 or third peak to peak value Vpp3 adjacent. In the electric leakage determination using the second peak peak value Vpp2, there is a possibility that it is erroneously determined that the electric leakage has occurred even though the electric leakage has not occurred. In control example 1, when the adjacent peaks and peaks Vpp do not substantially match, the leakage determination is invalid, so that an erroneous determination can be avoided.

As described above, according to the control example 1, the peak value without averaging is used for one peak value of the peak peak value Vpp, and the peak value before and after the peak value without averaging is used for the other peak value. Use the averaged peak value. As a result, one peak value of the peak peak value Vpp and the other peak value can be approximately set as voltage values acquired at the same time. By using the peak peak value Vpp based on the upper peak value and the lower peak value acquired at this virtually the same time, even when the voltage waveform at the measurement point A rises / falls at a constant speed as a whole. , Stable leakage detection is possible.

Therefore, if the voltage at the measurement point A deviates from the measurement range, the entire measurement voltage waveform returns to the state within the measurement range, and the voltage fluctuates in a sufficiently long cycle so as not to affect the leakage determination. Highly accurate leakage determination can be performed from the stage before the central potential of the measurement voltage returns to the intermediate potential (2.5V) of the measurement range. Therefore, it is possible to shorten the period during which the leakage determination cannot be performed.

Also, when the measured voltage fluctuates in a sufficiently long cycle, the two adjacent peaks and peak values Vpp substantially match. From this property, it is possible to determine the presence or absence of the influence of noise by comparing two adjacent peak peak values Vpp.

(Control example 2)
In control example 2, the leakage determination unit 11c calculates the virtual upper peak value by weight-averaging a plurality of voltage values measured at a plurality of times when the upper peak value should be measured, and the lower peak value is measured. A plurality of voltage values measured at a plurality of times to be measured are weighted and averaged to calculate a virtual lower peak value in which the virtual upper peak value and the time axis are aligned. The earth leakage determination unit 11c calculates the peak peak value Vpp between the calculated virtual upper peak value and the lower virtual peak value.

6 (a)-(b) are diagrams for explaining the difference in the calculation method of the peak peak value of the measured voltage waveform between the control example 1 and the control example 2. FIG. 6A shows a method of calculating the peak peak value of the measured voltage waveform in Control Example 1, and FIG. 6B shows a method of calculating the peak peak value of the measured voltage waveform in Control Example 2. In the control example 1 shown in FIG. 6 (a), the upper peak value V _H 1 is derived without averaging, and the lower peak value _VL μ is averaging two points sandwiching the upper peak value V _H 1. Derived.

In FIG. 6 (b) Control Example shown in 2, so that the time axis of the upper peak value V _H mu and the lower peak value V _L mu fits, the upper peak value V _H mu and the lower peak value and a weighted average, respectively _VL μ is derived. For example, the earth leakage determination unit 11c uses an FIR (Finite Impulse Response) filter to derive an upper peak value V _H μ and a lower peak value V _L μ that are virtually acquired at the same time. For example, the following (Equation 1) and (Equation 2) are calculated to derive the upper peak value V _H μ and the lower peak value V _L μ.

V _H μ = (V _H 1 × 3/4) + (V _H 2 × 1/4) ・・・ (Equation 1)
_VL μ = ( _VL 1 × 1/4) + ( _VL 2 × 3/4) ・・・ (Equation 2)

7 (a)-(b) are waveform diagrams showing an example of the peak peak value with respect to the frequency of the measured voltage in the control example 1 and the control example 2. 8 (a)-(b) are graphs showing an example of the gain characteristic with respect to the frequency of the measured voltage in the control example 1 and the control example 2. In FIGS. 7 (a)-(b), the thick dotted line shows an ideal voltage waveform on which noise is not superimposed. The thick solid line shows the actually measured voltage waveform on which noise is superimposed. In FIGS. 8A to 8B, the dotted line shows the gain characteristic of the upper peak value, and the solid line shows the gain characteristic of the lower peak value.

In Control Example 1, as shown in FIGS. 7 (a) and 8 (a), the lower peak value V _L μ is averaged, but the upper peak value V _H 1 is not averaged. Since the lower peak value _VL μ is averaged, noise is reduced around a frequency that is half the reference frequency. On the other hand, the upper peak value _VH 1 does not reduce noise. In FIG. 8A, the difference between the dotted line and the solid line in the vertical direction is an error. In the examples shown in FIGS. 7A and 8A, the error is maximum when the frequency is 0.5 Hz.

In Control Example 2, as shown in FIGS. 7 (b) and 8 (b), FIR filters are applied to both the upper peak value V _H μ and the lower peak value V _L μ. Therefore, in addition to the phase characteristic, the gain characteristic with respect to the frequency can be matched between the upper peak value V _H μ and the lower peak value V _L μ. Therefore, the influence of noise can be reduced. Comparing FIGS. 7 (a) and 7 (b), it can be seen that the peak peak value Vpp of the thick solid line shown in FIG. 7 (b) is closer to the peak peak value of the ideal voltage waveform.

As described above, according to Control Example 2, the upper peak value and the lower peak value of the peak peak value Vpp are calculated by weighted averaging as if they were virtually acquired at the same time. As a result, the gain characteristic with respect to the frequency can be matched, and the noise immunity can be improved. When the peak value based on the upper peak value and the lower peak value, which are simply averaged, are used without aligning the time axis, the measured voltage waveform as a whole is as shown in FIG. 4 (a). When ascending / descending at a constant speed, stable leakage detection cannot be performed.

The present disclosure has been described above based on the embodiment. Embodiments are exemplary, and it will be appreciated by those skilled in the art that various modifications are possible for each of these components and combinations of processing processes, and that such modifications are also within the scope of the present disclosure. ..

In the control examples 1 and 2 described above, an example of calculating the upper peak value and / or the lower peak value by filtering at two points has been described. At this point, the upper peak value and / or the lower peak value may be calculated by filtering at three or more points. In either case, it is sufficient that the time axes of the upper peak value and the lower peak value are aligned. In addition, in the example of calculating the upper peak value and / or the lower peak value by the two-point filtering process, the leakage can be detected earliest. The more sample points used for filtering, the better the reliability.

In the above-described embodiment, an example of applying a rectangular wave voltage from the voltage output unit to the coupling capacitor Cc via the first resistor R1 has been described. At this point, a sinusoidal voltage may be applied to the coupling capacitor Cc. In this case as well, the leakage determination unit 11c can specify the reference potential, the upper peak value, and the lower peak value from the voltage at the measurement point A, and determine the presence or absence of leakage as in the embodiment.

In the above-described embodiment, an example in which the leakage detection device 10 is mounted on an electric vehicle and used has been described. In this respect, the earth leakage detection device 10 according to the embodiment can be applied to applications other than in-vehicle applications. The load may be any load as long as the power storage unit 20 and the load receiving power from the power storage unit 20 are insulated from the ground. For example, it may be a load used in a railroad vehicle.

The embodiment may be specified by the following items.

[Item 1]
A coupling capacitor (Cc) whose one end is connected to the current path of the power storage unit (20) connected to the load (2) while being insulated from the ground.
A voltage output unit (11a, G1) that generates a periodic voltage that changes periodically and applies it to the other end of the coupling capacitor (Cc) via an impedance element (R1).
A voltage measuring unit (11b) for measuring the voltage at the connection point between the coupling capacitor (Cc) and the impedance element (R1), and
Based on the peak peak value between the upper peak value and the lower peak value of the voltage waveform measured by the voltage measuring unit (11b), the leakage between the current path of the power storage unit (20) and the ground A leakage determination unit (11c) for determining the presence or absence is provided.
The earth leakage determination unit (11c) estimates at least one of the upper peak value and the lower peak value at a certain time, and the peak between the upper peak value and the lower peak value whose time axes are virtually aligned. An earth leakage detection device (10), characterized in that a peak value is calculated.
According to this, even when the voltage waveform at the measurement point rises / falls as a whole, highly accurate leakage detection becomes possible.
[Item 2]
The earth leakage determination unit (11c) measures the voltage value measured at a time that should be measured one time before the specific upper peak value and one time after the specific upper peak value. It is characterized in that a virtual lower peak value is calculated by averaging the voltage values measured at an appropriate time, and a peak peak value between the specific upper peak value and the virtual lower peak value is calculated. The leakage detection device (10) according to item 1.
According to this, when the voltage waveform of the measurement point rises / falls as a whole, low-delay leakage detection becomes possible.
[Item 3]
The earth leakage determination unit (11c) has a voltage value measured at a time that should be measured one time before the specific lower peak value and one time after the specific lower peak value. The feature is that the virtual upper peak value is calculated by averaging the voltage values measured at the time to be measured, and the peak peak value between the specific lower peak value and the virtual upper peak value is calculated. The leakage detection device (10) according to item 1.
According to this, when the voltage waveform of the measurement point rises / falls as a whole, low-delay leakage detection becomes possible.
[Item 4]
The earth leakage determination unit (11c) calculates a virtual upper peak value by weighted averaging a plurality of voltage values measured at a plurality of times when the upper peak value should be measured, and measures the lower peak value. A plurality of voltage values measured at a plurality of times should be weighted and averaged to calculate a virtual lower peak value in which the virtual upper peak value and the time axis are aligned, and the virtual upper peak value and the virtual lower peak are calculated. The leakage detection device (10) according to item 1, wherein a peak value between the value and the value is calculated.
According to this, when the voltage waveform at the measurement point rises / falls as a whole, leakage detection with high noise immunity becomes possible.
[Item 5]
Any of items 1 to 4, wherein the earth leakage determination unit (11c) compares two adjacent peak peak values and evaluates the reliability of the earth leakage determination of the current path of the power storage unit (20). The leakage detection device (10) according to item 1.
According to this, the influence of noise can be confirmed.
[Item 6]
A power storage unit (20) that is mounted in a state of being insulated from the chassis ground of the vehicle and supplies electric power to the load (2) in the vehicle.
The earth leakage detection device (10) according to any one of items 1 to 5 and
A vehicle power supply system (5), which comprises.
According to this, even when the voltage waveform of the measurement point rises / falls as a whole, it is possible to realize a vehicle power supply system (5) equipped with a leakage detection device (10) capable of highly accurate leakage detection. it can.

2 Inverter, 3 Motor, Lp plus wiring, Lm minus wiring, Cp positive side Y capacitor, Cm negative side Y capacitor, Rlp positive side leakage resistance, Rlm negative side leakage resistance, 5 power supply system, 20 power storage unit, E1 to En cell , 10 Leakage detection device, 11 Control unit, 11a Oscillation unit, 11b Voltage measurement unit, 11c Leakage determination unit, Cc coupling capacitor, R1 1st resistor, R2 2nd resistor, OP1 1st operational amplifier, G1 AND gate, ZD1 1st 1 Zener diode, ZD2 2nd Zener diode.

Claims

A coupling capacitor whose one end is connected to the current path of the power storage unit connected to the load while being insulated from the ground.
A voltage output unit that generates a periodic voltage that changes periodically and applies it to the other end of the coupling capacitor via an impedance element.
A voltage measuring unit that measures the voltage at the connection point between the coupling capacitor and the impedance element,
Leakage determination to determine the presence or absence of leakage between the current path of the power storage unit and the ground based on the peak peak value between the upper peak value and the lower peak value of the voltage waveform measured by the voltage measuring unit. With a department,
The earth leakage determination unit estimates at least one of the upper peak value and the lower peak value at a certain time, and determines the peak peak value between the upper peak value and the lower peak value whose time axes are virtually aligned. An earth leakage detection device characterized by calculating.
The earth leakage determination unit has a voltage value measured at a time that should be measured one time before the specific upper peak value and a time that should be measured one time after the specific upper peak value. 1. The voltage value measured in 1) is averaged to calculate a virtual lower peak value, and a peak peak value between the specific upper peak value and the virtual lower peak value is calculated. Leakage detection device according to.
The earth leakage determination unit measures the voltage value measured at a time that should be measured one time before the specific lower peak value and one time after the specific lower peak value. A claim characterized in that the virtual upper peak value is calculated by averaging the voltage values measured at the appropriate time, and the peak peak value between the specific lower peak value and the virtual upper peak value is calculated. Item 1. The leakage detection device according to Item 1.
The earth leakage determination unit calculates a virtual upper peak value by weighted averaging a plurality of voltage values measured at a plurality of times when the upper peak value should be measured, and a plurality of lower peak values to be measured. A plurality of voltage values measured at time are weighted and averaged to calculate a virtual lower peak value in which the virtual upper peak value and the time axis are aligned, and the virtual upper peak value and the virtual lower peak value are combined. The earth leakage detection device according to claim 1, wherein the peak value between the peaks is calculated.
The item according to any one of claims 1 to 4, wherein the earth leakage determination unit evaluates the reliability of the earth leakage determination of the current path of the power storage unit by comparing two adjacent peak peak values. Leakage detector.
A power storage unit that is mounted in an insulated state from the chassis ground of the vehicle and supplies electric power to the load inside the vehicle.
The earth leakage detection device according to any one of claims 1 to 5.
A vehicle power supply system characterized by being equipped with.